/**
 * Dependency-free chart math, palette, and formatting helpers shared across
 * the charts/ family. Pure functions only — unit-tested in chart.utils.test.ts.
 *
 * Following the repo's zero-dependency philosophy (see Sankey's embedded
 * layout and the custom tv() engine), charts hand-roll their scales rather
 * than pulling in d3.
 */
/** A point in plot-local SVG coordinates. */
export type ChartPoint = [x: number, y: number];
/** Inclusive `[min, max]` of a numeric array; `[0, 0]` for an empty array. */
export declare function extent(values: readonly number[]): [number, number];
/**
 * Linear mapping from a numeric `domain` onto a pixel `range`. A zero-width
 * domain collapses to the range start (avoids divide-by-zero → NaN coords).
 */
export declare function linearScale(domain: [number, number], range: [number, number]): (value: number) => number;
/** Categorical band scale over `count` items across a pixel `range`. */
export interface BandScale {
    /** Left edge of band `index`. */
    position(index: number): number;
    /** Center of band `index` (use for line/scatter x). */
    center(index: number): number;
    /** Rendered width of a single band (step minus padding). */
    bandwidth: number;
    /** Distance between consecutive band starts. */
    step: number;
}
/**
 * Evenly spaced categorical bands with inner padding. `padding` is the
 * fraction (0–1) of each step left empty around bands.
 */
export declare function bandScale(count: number, range: [number, number], padding?: number): BandScale;
/**
 * Round a raw `[min, max]` outward to "nice" round bounds suitable for an
 * axis and return evenly spaced tick values within them (Heckbert's
 * algorithm). With `includeZero` (default) the domain always reaches zero
 * for single-signed data so bars sit on a real baseline.
 */
export declare function niceScale(rawMin: number, rawMax: number, tickCount?: number, includeZero?: boolean): {
    min: number;
    max: number;
    ticks: number[];
};
/** SVG path `d` for a polyline through `points` (straight segments). */
export declare function linePath(points: readonly ChartPoint[]): string;
/** SVG path `d` for a filled area between `points` and a horizontal `baselineY`. */
export declare function areaPath(points: readonly ChartPoint[], baselineY: number): string;
/**
 * SVG path `d` for a donut/pie segment between `startAngle` and `endAngle`
 * (radians, clockwise from 12 o'clock). `innerRadius` of 0 yields a filled pie
 * slice. A full-circle sweep is split into two arcs so it renders as a ring
 * rather than collapsing to a point.
 */
export declare function arcPath(cx: number, cy: number, outerRadius: number, innerRadius: number, startAngle: number, endAngle: number): string;
/**
 * Ordered categorical palette mapped to the `--color-chart-*` tokens
 * (declared in `style/semantic.css`). Cycles for series beyond its length.
 */
export declare const chartPalette: readonly string[];
/** Resolve a series color: explicit override wins, else cycle the palette. */
export declare function seriesColor(index: number, explicit?: string, palette?: readonly string[]): string;
/**
 * A locale-aware number formatter. Falls back to `String(value)` if `Intl`
 * is unavailable (defensive — present in every modern browser + SSR runtime).
 */
export declare function numberFormatter(locale?: string, options?: Intl.NumberFormatOptions): (value: number) => string;